Process for manufacturing silanized (meth) acrylates

ABSTRACT

The silanized (meth)acrylate (I) is manufactured by reacting the anhydride (II) with a silanized compound (III). This process gives a crude mixture containing compound (IV) in addition to compound (I), after which the said mixture may be freed of the lightest compounds by distillation or may be subjected to a distillation to obtain the pure compound (I).  
                 
 
     R=H or Me; R 1 , R 2 , R 3 =linear or branched C 1 -C 10  alkyl, aryl or aralkyl, these radicals possibly being substituted and possibly containing hetero atoms; R 4 =H or a radical falling within the definition given above for R 1 , R 2  and R 3 .

[0001] The present invention relates to a process for manufacturing a silanized (meth)acrylate of formula:

[0002] in which:

[0003] R represents hydrogen or methyl;

[0004] R¹, R² and R³ each independently represent a linear or branched C₁-C₁₀ alkyl radical, an aryl radical or an aralkyl radical, these radicals possibly being substituted and possibly containing hetero atoms.

[0005] The (meth)acrylates (I) are known for their use as hydrolysable monomers which serve for the preparation of binders in the field of self-smoothing antifouling marine paints intended, for example, for coating the hulls of boats or more generally of materials in contact with a marine environment (U.S. Pat. Nos. 4,593,055 and 4,687,792).

[0006] Various synthetic routes are described in the literature for manufacturing these silanized (meth)acrylates. These may be grouped in Table 1 below: TABLE 1 SYNTHETIC ROUTE DOCUMENTS DRAWBACKS 1

J. Polym. Sci. A1, 8, 319 (1970) Eur. Polym. J. vol. 28, n 4, pages 335-338 (1992) US-A-4 593 055 JP-A-04 342 593 JP-A-04 342 595 use of chlorosilane, an expensive reagent formation of a large amount of hydrochloride which is to be separated out by filtration 2

JP-A-05 025 188 formation of a large amount of disiloxane R¹R²R³SiOSiR¹R²R³ 3

JP-A-04 154 790 JP-A-05 25 187 JP-A-10 195 084 JP-A-10 212 293 generation of H₂(implementation problem - safety; addition of H₂ to the double bond) 4

Pierce, Silylation of organic compounds (1968) Kashutina, Usp. Khim. 44, 1620 (1975) synthetic route specific for trimethylsilyl (meth)acrylates 5

EP-A-0 131 626 use of (meth)acryloyl chloride HCl as by-product 6

Tsuruta, Bull. Inst. Res. Kyoto Univ. 40, 151 (1962) Andreev, Zh. Obschch. Khim, 30, 2782 (1960) use of Ag salt solid precipitate to be separated out by filtration 7

Eur. Polym. J. vol. 28, n 4, pages 335-339 (1992) precipitate of KCl to be separated out by filtration

[0007] The synthetic routes described in Table 1 present, in one way or another, a number of drawbacks that the Applicant Company has succeeded in overcoming by carrying out the synthesis using (meth)acrylic anhydride and a silanized alkoxylated or hydroxylated derivative.

[0008] The process according to the invention for preparing the silanized (meth)acrylates (I) defined above allows them to be obtained under good conditions of conversion, selectivity and production efficiency, without waste products, without separation solids and without generation of H₂. Thus, the manufacture of the silanized (meth)acrylates (I) according to the present invention may be carried out in total safety in simple stirred, heated stainless-steel reactors, in contrast with processes which generate H₂ or HCl as by-products; in addition, it does not require any labour-intensive individual steps of the type such as filtration, washing or drying of solids.

[0009] A first subject of the present invention is thus a process for manufacturing a silanized (meth)acrylate of formula (I), as defined above, characterized in that the anhydride of formula (II):

[0010] in which R is as defined above, is reacted with a silanized compound of formula (III)

[0011] in which:

[0012] R¹, R² and R³ are as defined above; and

[0013] R⁴ represents hydrogen or a radical falling within the definition given above for R¹, R² and R³.

[0014] R¹, R², R³ and R⁴ are chosen especially from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl and alkylphenyl radicals with alkyl being C₁-C₁₀, R⁴ also possibly being hydrogen. R⁴ is preferably chosen from hydrogen, ethyl, n-propyl and n-butyl.

[0015] As indicated above, the radicals R¹ to R³ may be substituted, for example, with halogen atoms, such as Cl or Br, or groups —NR⁵R⁶ (R⁵ and R6 representing C₁ to C₈ alkyl groups); moreover, the chain of these radicals may be interrupted with a hetero atom such as O or S.

[0016] The reaction of the invention is generally performed with a compound (II)/compound (III) molar ratio of between 0.3/1 and 3/1, although molar ratios of less than 0.3/1 or greater than 3/1 can theoretically be used. In accordance with one preferred embodiment of the invention, the reaction is performed with a compound (II)/compound (III) molar ratio of between 0.7/1 and 2/1 and preferably between 0.9/1 and 1.2/1.

[0017] The reaction is performed at a temperature of from 20 to 200° C., preferably from 75 to 100° C., in particular from 80 to 120° C., and preferably at atmospheric pressure, although it is possible to perform the process under a pressure above or below atmospheric pressure.

[0018] Moreover, the reaction is performed to the point of maximum conversion of the reagents, determined using the usual analytical methods, for example such as gas chromatography. The reaction time depends on the operating conditions and on the reagents (II) and (III) used in the synthesis. It is generally between 3 and 8 hours.

[0019] The reaction (acylation) may be carried out with or without a catalyst. The use of a catalyst makes it possible to prevent the formation of disiloxanes, to increase the reaction kinetics and, as a result, to reduce the reaction time.

[0020] Among the catalysts which may be used, individually or as a mixture of two or more, mention may be made of 1-methylimidazole, dimethylaminopyridine, 4-pyrroli-dinopyridine, 4-piperidinopyridine, 4-morpholinopyridine, triflates, tributylphosphine, triethylamine, pyridine, montmorillonites such as montmorillonite K10 and KSF, protic acids such as para-toluenesulphonic acid and Lewis acids such as ZnCl₂, the catalyst(s) generally being used in a proportion of from 0.05 to 1% by weight relative to the mixture of reagents. The use of larger amounts of catalyst is possible, although this does not provide an additional gain in terms of reducing the reaction time. 1-Methylimidazole is the preferred catalyst.

[0021] Moreover, the process according to the present invention is generally carried out in the presence of at least one polymerization inhibitor chosen especially from hydroquinone, hydroquinone methyl ether, phenothiazine, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy (TEMPO) and homologues thereof such as 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy, 2,2,6,6-tetramethyl-1-piperidinyloxy, 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy, 4-methoxy-2,2,6,6-tetramethyl-1-piperidinyloxy and 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy, and hindered phenolic inhibitors such as 2,4-dimethyl-6-tert-butylphenol and 2,6-di-tert-butyl-para-cresol, and homologues thereof, the polymerization inhibitors) being used in a proportion of from 0.05 to 0.5% by weight relative to the mixture of reagents.

[0022] The reaction according to the invention is advantageously carried out in the presence of air. The end of the reaction is determined by analysing the reaction medium (for example by GC).

[0023] The reaction according to the invention gives a crude mixture containing, besides compound (I), the compound of formula (IV) as a by-product:

[0024] in which R and R⁴ are as defined in claim 1, after which the said mixture may be freed of the lightest compounds by distillation (topping) or may be subjected, in order to obtain the pure compound (I), to a distillation, generally using a distillation column for the more volatile compounds (I) or a film evaporator for those with the highest boiling points.

[0025] The present invention also relates to the use of the crude mixture or of the mixture freed of the lightest compounds or of the pure compound (I), as obtained by the above process, as hydrolysable monomer(s) of a monomer composition whose polymerization gives a binder intended for self-smoothing antifouling marine paints. The binder is generally present in the paint composition in a proportion of from 10 to 30% by weight (in dry form).

[0026] The paint composition comprises the other usual ingredients, such as:

[0027] adjuvants, for instance soybean lecithin, modified hydrogenated castor oil or viscosity stabilizers (such as Viscostab CNF 896 manufactured by the company Atofina);

[0028] pigments and fillers, such as non-acicular zinc oxide, cuprous oxide and rutile titanium oxide; and

[0029] solvents and diluents such as the solvent naphtha, ioiuene and xylene.

[0030] The examples which follow illustrate the present invention without, however, limiting its scope. The percentages are expressed on a weight basis except where otherwise mentioned. The abbreviations used are as follows: AMA20 methacrylic anhydride AA20 acrylic anhydride AMA methacrylic acid AA acrylic acid MAM methyl methacrylate Bu3SiMA tributylsilyl methacrylate Bu3SiOSiBu3 hexabutyldisiloxane MAM methyl methacrylate Bu3SiOMe tributylmethoxysilane Bu3SiOH tributylsilanol Bu3SiH tributylsilane 1-MIM 1-methylimidazole (catalyst) BHT 2,6-di-tert-butyl-para-cresol (polymerization inhibitor) TOPANOL A 2,4-dimethyl-6-tert-butylphenol (polymerization inhibitor) Me methyl Et ethyl nOct n-octyl isoPro isopropyl nPro n-propyl Bu butyl nBu n-butyl isoBu isobutyl tBu tert-butyl

EXAMPLE 1 Preparation of Bu3SiMA from AMA20 and Bu3SiOMe

[0031] The following ingredients:

[0032] 43.2 g of 98% pure AMA20;

[0033] 59.5 g of 97% pure Bu3SiOMe;

[0034] 0.1 g of TOPANOL A;

[0035] 0.1 g of BHT; and

[0036] 0.5 g of 1-MIM,

[0037] are introduced into a glass reactor heated by circulation of thermostatically-maintained hot oil inside a jacket, mechanically stirred (stirrer of anchor type), on which is mounted a distillation column of Vigreux type with a head condenser, a reflux head, a vacuum separator and a trapping vessel.

[0038] The AMA20/Bu3SiOMe molar ratio is 1.1/1.

[0039] Air is bubbled through throughout the syntheses.

[0040] The mixture is heated at 110° C. for 5 hours with stirring. At the end of these 5 hours, the degree of conversion of Bu3SiOMe is greater than 96%. The Bu3SiMa content is 74%. The crude product is then distilled under vacuum.

[0041] A first head fraction F1 (13.4 g) is collected under a pressure of 26 664.48 to 13 332.24 Pa (200 to 100 mmHg); the fraction is more than 99% composed of MAM.

[0042] A fraction F2 (3.5 g) composed of a mixture of AMA20 and AMA is then distilled off.

[0043] The Bu3SiMA is distilled off under 533.29 Pa (4 mmHg) (reactor temperature from 140 to 180° C. at the end of the distillation/column head temperature of 138 to 142° C.).

[0044] 65 g of Bu3SiMa are thus recovered in a purity of 97%. The formation of Bu3SiOSiBu3 is negligible.

EXAMPLES 2 to 12 Preparation of Silanized (meth)Acrylates by the Reaction of, (meth)Acryli Anhyride and an Alkoxylated Silanized Compound

[0045]

[0046] 11 different syntheses are performed as in Example 1, but starting in each case:

[0047] with AMA20 or AA20 as compound (II) (R representing Me and H, respectively); and

[0048] with an alkoxylated silanized compound (III) in which the radicals R¹ to R⁴ are indicated in Table 1.

[0049] The said table also shows:

[0050] the composition of the reaction medium (in mol %) at the initial time ti and at the time tf of the end of the reaction (after 5 hours at 110° C.);

[0051] the degree of conversion DC (%) of compound (III), and

[0052] the yield Y (%) of compound (I). TABLE 2 Composition of the reaction medium (moles/100 g of crude product) Compound Compound Compound Compound (III) (II) (IV) (I) DC Y Example R R¹ R² R³ R⁴ ti tf ti tf ti tf ti tf (%) (%) 2 Me Me Me Me Me 0.36 0.04 0.39 0.05 0 0.32 0 0.34 >94 >99 3 Me Me Me nOct Me 0.26 0.01 0.29 0.03 0 0.24 0 0.26 >96 >99 4 Me Me Me Me Et 0.34 0.10 0.37 0.10 0 0.25 0 0.24 70 >99 5 Me Me Me Me nPro 0.32 0.10 0.36 0.12 0 0.20 0 0.23 68 >99 6 Me Me Me Me isoPro 0.32 0.15 0.36 0.19 0 0.14 0 0.17 53 >99 7 H Me Me Me Me 0.40 0.05 0.44 0.06 0 0.33 0 0.33 87 94 8 H Me Me nOct Me 0.28 0.05 0.33 0.07 0 0.22 0 0.215 82 93 9 H Bu Bu Bu Me 0.26 0.05 0.30 0.06 0 0.19 0 0.20 80 95 10 H Me Me Me Et 0.37 0.10 0.42 0.08 0 0.26 0 0.26 73 96 11 H Me Me Me nPro 0.35 0.07 0.40 0.08 0 0.22 0 0.25 80 89 12 H Me Me Me isoPro 0.35 0.10 0.40 0.12 0 0.18 0 0.20 71 80

EXAMPLE 13 Preparation of Bu3SiMA from AMA20 and Bu3SiOH

[0053] The process was performed as in Example 1, except that Bu3SiOH was used instead of Bu3SiOMe.

[0054] The Bu3SiOH used has the following composition by mass (in %): Bu3SiOH 91.4 Bu3SiOMe 0.9 Bu3SiOSiBu3 2.6 Bu3SiH 0.9 Others q.s. 100

[0055] The AMA20/Bu3SiOR molar ratio is 2/1.

[0056] After reaction for 6 hours at 110° C., the crude reaction product has the following composition by mass (in %): MAM 0.3 AMA 16.6 AMA20 27.4 Bu3SiOH 0.13 Bu3SiOMe 0.08 Bu3SiMA 48 Bu3SiOSiBu3 7.9

[0057] Some of the Bu3SiOH was consumed in the form of Bu3SiOSiBu3; the rest was converted into Bu3SiMA. 

1. Process for manufacturing a silanized (meth)acrylate of formula:

in which: R represents hydrogen or methyl; R¹, R² and R³ each independently represent a linear or branched C₁-C₁₀ alkyl radical, an aryl radical or an aralkyl radical, these radicals possibly being substituted and possibly containing hetero atoms characterized in that the anhydride of formula (II):

in which R is as defined above, is reacted with a silanized compound of formula (III)

in which: R¹, R² and R³ are as defined above; and R⁴ represents hydrogen or a radical falling within the definition given above for R¹, R² and R³.
 2. Process according to claim 1; characterized in that R¹, R², R³ and R⁴ are chosen from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl and alkylphenyl radicals with alkyl being C₁-C₁₀, R⁴ also possibly being hydrogen.
 3. Process according to either of claims 1 and 2, characterized in that the reaction is performed with a compound (II)/compound (III) molar ratio of between 0.3/1 and 3/1.
 4. Process according to claim 3, characterized in that the reaction is performed with a compound (II)/compound (III) molar ratio of between 0.7/1 and 2/1 and preferably between 0.9/1 and 1.2/1.
 5. Process according to one of claims 1 to 4, characterized in that the reaction is performed at a temperature of from 20 to 200° C., preferably from 75 to 100° C., in particular from 80 to 120° C.
 6. Process according to one of claims 1 to 5, characterized in that the reaction is performed at atmospheric pressure.
 7. Process according to one of claims 1 to 6, characterized in that the reaction is performed to the point of maximum conversion of the reagents, determined using the usual analytical methods.
 8. Process according to claim 7, characterized in that the reaction is performed for a period of from 3 to 8 hours.
 9. Process according to one of claims 1 to 8, characterized in that the reaction is performed in the presence of at least one catalyst chosen especially from 1-methylimidazole, dimethylamino-pyridine, 4-pyrrolidinopyridine, 4-piperidino-pyridine, 4-morpholinopyr4idine, triflates, tri-butylphosphine, triethylamine, pyridine, mont-morillonites, protic acids such as para-toluene-sulphonic acid and Lewis acids such as ZnCl₂ the catalysts) being used in a proportion of from 0.05 to 1% by weight relative to the mixture of reagents.
 10. Process according to one of claims 1 to 9, characterized in that the reaction is carried out in the presence of at least one polymerization inhibitor chosen especially from hydroquinone, hydroquinone methyl ether, phenothiazine, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy and homologues thereof such as 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy, 2,2,6,6-tetramethyl-1-piperidinyloxy, 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy, and 4-methoxy-2,2,6,6-tetramethyl-1-piperidinyloxy, and hindered phenolic inhibitors, the polymerization inhibitor(s) being used in a proportion of from 0.05 to 0.5% by weight relative to the mixture of reagents.
 11. Process according to one of claims 1 to 10, characterized in that it gives a crude mixture containing, besides compound (I) the compound of formula (IV):

in which R and R⁴ are as defined in claim 1, after which the said mixture may be freed of the lightest compounds by distialation or may be subjected to a distillation to obtain the pure compound (I)
 12. Use of the crude mixture or of the mixture freed of the lightest compounds or of the pure compound (I), as obtained by the process of claim 11, as hydrolysable monomers) of a monomer composition whose polymerization gives a binder intended for self-smoothing antifouling marine paints. 